Using json.net, how to disregard a property in a class if it is null.

Problem

To serialize a class to JSON, I’m using Json.NET.

This is how my class looks:

class Test1
{
    [JsonProperty("id")]
    public string ID { get; set; }
    [JsonProperty("label")]
    public string Label { get; set; }
    [JsonProperty("url")]
    public string URL { get; set; }
    [JsonProperty("item")]
    public List<Test2> Test2List { get; set; }
}

Only when Test2List is nil, I want to add a JsonIgnore() attribute to Test2List. I want to add it in my json if it isn’t null.

Asked by Amit

Solution #1

Another option is to use the JsonProperty attribute:

[JsonProperty(NullValueHandling=NullValueHandling.Ignore)]
// or
[JsonProperty("property_name", NullValueHandling=NullValueHandling.Ignore)]

// or for all properties in a class
[JsonObject(ItemNullValueHandling = NullValueHandling.Ignore)]

As can be seen in this internet document.

Answered by sirthomas

Solution #2

According to James Newton King, there is a NullValueHandling attribute that you can set to ignore if you write the serializer yourself rather than using JavaScriptConvert.

Here’s a sample:

JsonSerializer _jsonWriter = new JsonSerializer {
                                 NullValueHandling = NullValueHandling.Ignore
                             };

Alternatively, as @amit mentioned,

JsonConvert.SerializeObject(myObject, 
                            Newtonsoft.Json.Formatting.None, 
                            new JsonSerializerSettings { 
                                NullValueHandling = NullValueHandling.Ignore
                            });

Answered by Mrchief

Solution #3

If you don’t want to add Newtonsoft-specific characteristics to your mod, JSON.NET respects the EmitDefaultValue parameter on DataMemberAttribute.

[DataMember(Name="property_name", EmitDefaultValue=false)]

Answered by Tobias J

Solution #4

[JsonProperty(“property name”,DefaultValueHandling = DefaultValueHandling.Ignore)] is an example.

It also ensures that attributes with default values are not serialized (not only null). Enums, for example, can benefit from it.

Answered by Vatsal Patel

Solution #5

This allows you to disregard all nulls in an object while serializing it, and any null properties won’t appear in the JSON output.

JsonSerializerSettings settings = new JsonSerializerSettings();
settings.NullValueHandling = NullValueHandling.Ignore;
var myJson = JsonConvert.SerializeObject(myObject, settings);

Answered by Chris Halcrow

Post is based on https://stackoverflow.com/questions/6507889/how-to-ignore-a-property-in-class-if-null-using-json-net